A. Normal vessel. B, True aneurysm, saccular type. The wall focally bulges outward and may be attenuated but is otherwise intact. C, True aneurysm, fusiform type. There is circumferential dilation of the vessel, without rupture. D, False aneurysm. The wall is ruptured, and there is a collection of blood (hematoma) that is bounded externally by adherent extravascular tissues. E, Dissection. Blood has entered (dissected) the wall of the vessel and separated the layers. Although this is shown as occurring through a tear in the lumen, dissections can also occur by rupture of the vessels of the vaso vasorum within the media.
Morphological types of aneurysms
A large "bulge" appears just above the aortic bifurcation. Such aneurysms are prone to rupture when they reach about 6 to 7 cm in size. They may be felt on physical examination as a pulsatile mass in the abdomen. Most such aneurysms are located below the renal arteries so that surgical resection can be performed with placement of a dacron graft.
Atherosclerotic aneurysm of the abdominal aorta
A, External view, gross photograph of a large aortic aneurysm that ruptured (arrow). B, Opened view, with the location of the rupture tract indicated by a probe. The wall of the aneurysm is exceedingly thin, and the lumen is filled by a large quantity of layered but largely unorganized thrombus.
Abdominal aortic aneurysm
This aorta has been opened longitudinally to reveal an area of fairly limited dissection that is organizing. The red-brown hematoma can be seen in on both sides of the section as it extends around the aorta. The dissection creates a "double lumen" to the aorta. This aorta shows in addition severe atherosclerosis.
Aortic dissection
This aortic dissection occurred just above the aortic root in a patient with Marfan's syndrome. The tear extends across the aorta. Hemopericardium with tamponade occurred within minutes of this event.
Aortic dissection
an opened aorta with proximal dissection originating from a small, oblique intimal tear (identified by the probe), allowing blood to enter the media and create an intramural hematoma (narrow arrows). Note that the intimal tear has occurred in a region largely free of atherosclerotic plaque and that propagation of the intramural hematoma is arrested at a site more distally where atherosclerosis begins (broad arrow).
Aortic dissection
The dissection goes into the muscular wall creating an aorta with double lumina.
Aortic dissectionOriginal lumen
Dissection
Aortic dissection: medial cystic degeneration
This special stain highlight the elastic fibers of the aortic wall. There is extensive fragmentation & destruction of the fibers associated with several coalescent cystic areas within the wall.The right carotid artery is compressed by blood dissecting upward from a tear with aortic dissection. Blood may also dissect to coronary arteries. Thus patients with aortic dissection may have symptoms of severe chest pain (for distal dissection) or may present with findings that suggest a stroke (with carotid dissection) or myocardial ischemia (with coronary dissection).
Extension of aortic dissection
The aortic root is widened here and the commissures of the aortic valve cusps are pulled apart. The aorta above this shows peculiar wrinkling that is typical for syphilitic aortitis. The widening of the root can cause aortic insufficiency and also aneurysmal dilation of the ascending aorta. Such dilation may also be seen with Marfan's syndrome, but the intima would not show the wrinkling.
Syphilitic aneurysm
The surface of the aorta shows wrinkling or "tree-barking" that is typical for syphilitic aortitis. The aortitis involves the vasa vasora and leads to focal medial loss that produces the wrinkling.
Syphilitic aneurysm
A case of syphilitic aortitis showing lymphoplasmacytic infiltration of the vasa vasorum within the aortic adventitia.
Syphilitic aortitis
Circle of Willis with anterior, middle and posterior cerebral arteries linked by communicating vessels. Berry aneurysms are seen arising where the internal carotid bifurcates into middle and anterior cerebral arteries (arrow).
Berry aneurysms
Blood is present in the sub-arachnoid space over the cerebellum. in this case the aneurysm was arising at the tip of the basilar artery.
Ruptured Berry aneurysm with subarachnoid Hge